How is Load Power calculated. Solar i-boost impact ?

Looking at my dashboard I can see that once my battery hits 100% full the load power is practically the same (fractionally less) as the Solar generation, until the sun goes in (when it looks more like it would if it just showed the power I was consuming). On other days, when at 100%, the export energy is higher and the load power correspondingly less.
I'm guessing that I don't really understand how / where the load power is calculated.
I have a Solar I-Boost that kicks in when the battery is 100 % full and I'm guessing the load power is including the power used by the i-boost and that's why the load power and solar output match.
As an aside I don't have an i-boost buddy so does this mean that when I can see the load power drop and the export go up I can assume the hot water tank is at it's maximum heat ?

jkraushaar to your last comment yes. As soon as the hot water is hot it then exports excess to the grid.
I heat our hot water with gas in the morning and the the innersun solar diverter kicks in. But I also monitor the consumption of the diverter with a energy monitor - (In this case a Schneider wireless ct as it’s a dedicated circuit - it was something I obtained from work as it was surplus to requirements).